The present invention relates to a liquid crystal display device having a panel connected to an IC chip mounted on a narrow film wiring board.
A liquid crystal display device has a liquid crystal display panel and an IC chip for driving the liquid crystal display panel. U.S. Pat. No. 4,799,771 discloses a liquid crystal display device comprising a liquid crystal display panel and a plurality of IC modules. The IC modules, for driving scanning electrodes and data electrodes, are arranged on sides of the panel. Each IC module is mounted on a film wiring board called a carrier tape, which is generally called a TCP (Tape Carrier Package). The scanning and data electrodes are arranged on each side of the liquid crystal display panel along its entire length. They are connected by, for example, anisotropic conductive adhesive, to lead terminals formed on the carrier tape on which each IC module is mounted. At this time, naturally, the electrodes are positioned and bonded to the lead terminals in every IC chip. Therefore, the more the number of IC modules, the longer the required process time.
Recently, the electrodes of an IC chip can be arranged at a very small pitch, owing to the high integration of IC chips and the progress of the bonding technique. However, so long as the lead terminals formed on a carrier tape are connected to the scanning electrodes or the data electrodes arranged on a liquid crystal display panel, the width of the carrier tape cannot be reduced. This matter will be described in detail with reference to FIG. 5. A liquid crystal display panel 1 is constituted by a segment (data) substrate 2 on the upper side and a common (scanning) substrate 3 on the lower side adhered by a substantially frame-shaped sealing member (not shown), and liquid crystal (not shown) sealed within a space between the substrates 2 and 3 enclosed by the sealing member. The segment substrate 2 is longer than the common substrate 3. A side portion 2a of one of the long sides is projected from a lower edge of the common substrate 3. A number of contact terminals 5 are formed on the lower face of the projected portion 2a.
An IC module 21 of this liquid crystal display device has a film wiring board 22. The film wiring board 22 has a substantially rectangular portion and a square projected portion projected from a central portion of the lower end of the rectangular portion. The width in the lateral direction of the drawing of the rectangular portion is slightly smaller than the width in the lateral direction of the liquid crystal display panel 1. A semiconductor chip 23 made of an LSI or the like, for driving the liquid crystal display panel 1, is mounted on a substantially central portion of the film wiring board 22.
Lead wires 24, 25 and 26 are formed on the upper surface of the film wiring board 22. First ends of the lead wires 24 are connected to electrodes arranged along a long side of the semiconductor chip 23. Second ends thereof are connected to those parts of contact terminals 5 which are located in a central portion of the projected portion 2a of the liquid crystal display panel 1. First ends of the lead wires 25 and 26 are connected to electrodes arranged along the short sides of the semiconductor chip 23. Second ends thereof are connected to those parts of the contact terminals 5 which are arranged in side portions of an end of the projected portion 2a of the liquid crystal display panel 1.
Since the lead wires 24, 25 and 26 are connected to the contact terminals arranged substantially along the entire length of the liquid crystal display panel 1, the width w.sub.t of the film wiring board 22 is almost the same as the width w.sub.p of the liquid crystal display panel 1. Therefore, if film wiring boards 22 are obtained by cutting a long base film, merely a small number of film wiring boards can be produced, resulting in a high cost. In addition, since the mounting area is large, the degree of freedom of mounting is small. Moreover, since the wiring board is liable to receive external force, reliable interconnection cannot be achieved.